characterization of finger millet blast pathogen (pyricularia grisea) and its management using...
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Presented by Getachew Gashaw, Tesfaye Alemu and Kassahun Tesfaye at the First Bio-Innovate Regional Scientific Conference, Addis Ababa, Ethiopia, 25-27 February 2013TRANSCRIPT
First Bio-Innovate Regional Scientific ConferenceUnited Nations Conference Centre (UNCC-ECA)Addis Ababa, Ethiopia, 25-27 February 2013
Characterization of Finger Millet Blast Pathogen (Pyricularia grisea) and Its Management Using
Biocontrol Agents and Fungicides
Getachew Gashaw, Tesfaye Alemu and Kassahun Tesfaye
Content outline
Introduction
Objectives
Materials and methods
Results and Discussions
Conclusions and Recommendations
Acknowledgment
1. Introduction
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2. Specific Objectives
To isolate and characterize finger millet blast pathogen from
various areas
To study the effect of different cultural and growth factors of
Pyricularia grisea in the laboratory
To carry out pathogenicity test and estimate the yield losses
caused by Pyricularia grisea
To evaluate In Vitro antagonistic activities of Trichoderma and
Pseudomonas species and fungicides against P. grisea3
3. Materials and Methods
Experimental site
Mycological Research Laboratory
In Vivo experimental conducted in the Department of Microbial,
Cellular and Molecular Biology, Addis Ababa University
Study areas and samples collection
(East and West Welega, Metekel, Awi, and West Gojam)
The survey route followed major roads to towns and localities
in
45 districts separated by 10-12 km from each other 4
Isolation of Pyricularia grisea
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Cultural and morphological characterizations of P. grisea
Surface texture, pigmentation and mycelial growth
on different solid media
All the media were sterilized, at 121°C for 15 minutes
Colony diameters of each isolate in plates were measured in
millimeter, at two days intervals for 10 days
Mycelial colour, type of margin and sporulation were recorded
Shape, colour, size (length & width), septation of conidia
6
Effect of temperature levels on growth of P. grisea isolates
Six isolates of Pyricularia grisea were grown on malt extract
agar, at six temperatures (15, 20, 25, 30, 35 and 40OC)
Colony diameters of each isolate were measured in millimeter
Effect of hydrogen ion concentration(pH) on P. grisea isolates
Potato dextrose broth medium was used
pH levels (3, 3.5, 4, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5 and 8.0)
The dry weight of each isolate was measured
Carbon and Nitrogen utilizations P. grisea isolates
Richards’s medium was used (Otsuka et al., 1957)7
Pathogenicity test
Evaluation of Finger millet varieties under green house condition
Boneya, Local Check and Tadesse obtained from BARC
sown in 21cm plastic pots filled with 5kg of autoclaved soil
When the seedlings were six weeks old the leaves were;
cleaned with sterile distilled water & predisposed to nearly 95%
humidity for 24 hours (Sreenivasaprasad et al., 2005)
Spore suspensions of 15 days old culture were adjusted to the
concentration of 105spore/ml for all isolates
Six weeks old finger millet seedlings were inoculated by spraying
on leaves by using hand sprayer (Han et al., 2003) with controls 8
Pathogenicity test
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a. Conidia spray on the foliage b. Incubation of seedlings
Blast disease assessment
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Disease assessment cont’d….
Blast DS and DI was assessed according to the scale of Waller
et al. (2002); DS% = nxv/9N x100; Where:
(n)= Number of plants in each category,
(v) = Numerical values of symptoms category.
(N)= Total number of plants,
(9) = Maximum numerical value of symptom category.
DI (%) = Number of infected plant units X 100
Total number (healthy and infected of units assessed)
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Assessment of yield losses
Finger millet yield loss was calculated using the equation
developed by Mousanejad et al. (2010).
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In Vitro evaluation of biocontrol agents and fungicides against P. grisea isolatesT. harzianum (AUT1), T. viride (AUT2), and P. fluorescens
Dual culture method used (Rao, 2003, and Rangajaran et al., 2003)
Percentage of radial growth inhibition was calculated by
Riungu et al. (2008)
The poisoned food technique (Nine and Thapliyal, 1993)
Stock concentrations of the fungicides (a.i) were used
Bayleton 50%, Curzate 43.95%, Ridomil 68%, Sancozeb 80%
Relative growth reduction for each rate of fungicide was calculated
by Riungu et al. 2008.
One way ANOV procedures of SPSS statistical analysis software 13
4. RESULTS AND DISCUSSIONS
Isolation of finger millet blast (Pyricularia grisea) isolates
42 isolates of P. grisea isolated from diseased leaf, neck and
finger/seed of finger millet weed and wild relative species from
different locations
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Cultural and morphological characteristics of P. grisea isolates
Cultural characteristicsThe colony of the isolates showed significant differences Growth rate and slight variations in colour
Colony colors, isolates imparted on the different growth media
Gray, greyish black, black and buff white colors
Awoderu et al. (1991); Meena (2005)
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Pg.11 Pg.20 Pg.22Pg.26 Pg.40 Pg. 41
HSEA
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Table 1. Evaluation of culture media for the growth of P. grisea
Conidial characteristics of P. grisea isolates
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Shape of conidia
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Pg.11 Pg.20
Fig. 1. Microscopic observation of morphology of P. grisea isolates
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Fig.2 Conidia and conidiophores of Pyricularia grisea isolates
Mijan (2000)
No. Isolate Range(μm) Average (μm)
1 Pg.11 21.05-28.80 x 6.55-9.54 19.35 x 6.85
2 Pg.20 18.01-24.03 x 6.84-10.28 20.50 x 8.77
3 Pg.22 15.66-24.37 x 7.70-12.90 18.32 x 10.57
4 Pg.26 22.79-29.77 x 6.87-12.13 23.98 x 9.50
5 Pg.40 24.36-29.48 x 8.35-11.92 25.72 x 10.14
6 Pg.41 26.91-35.43 x 6.35-9.20 31.17 x 7.7820
Table 2. Conidial size of the six isolates of the pathogen after 10 days incubation, at 27±1oC
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Table 3. Evaluation of mycelial growth of P.grisea at different temperature levels
Similarly, Arunkumar and Singh (1995) ;Suryanarayanan, (1996)
Table 4. Dry mycelial weight of the isolates of Pyricularia grisea at different pH level
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Table 5. Effects carbon sources on mycelial growth of P. grisea isolates
Tochinai and Nakano (1940); Otsuka et al. (1965); Onofeghara et al. (1973)
Table 6. Effect of nitrogen sources on mycelial growth of P. grisea isolates
25Apparao (1956); Otsuka et al. (1965)
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Table 7. Average disease incidences and severities and their ranges in different agro climatic Regions of Ethiopia.
Values in the same letters are not significantly different
Ecological
zone
Disease
incidence
(%)
Av. disease
incidence
(% ) ±SD
Disease
severity
(%)
Av. disease
severity
(%)±SD
Altitude
Mean±SD
East
Wellega
35-68.3 54.1±10.30a 18-35.8 28.6±6.7ab 1862.1±165.9ab
West
Wellega
45-76.7 63.03±11.04a 22.5-50 34.6±8.4a 1726.2±129.7b
Metekel 10-75 50.8±26.5a 0-25 22.3±23.1ab 1152±153.8c
Awi 20-65 46.7±15.00a 5-27 15.7±8.1b 1913.3±277.9ab
West
Gojjam
37-95 57.9±16.5a 5-69 23.7±16.3ab 1990.4±185.9a
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Table 8. Percentage of disease incidence and severity under green house condition
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Table 9. Assessment of yield losses caused by P. grisea isolates on the three finger millet varieties under green house condition
Takan et al. (2004); Adipala (1989); Ahmad et al. (2011)
Table10. In vitro evaluation of antagonistic activity of Trichoderma species and P. fluorescens against P. grisea isolates
29Harish et al. (2007) ; Rosales et al. (1995)
In vitro testing cont’d……..
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Pg.11 Pg.20 Pg.22
Pg.41Pg.26 Pg.40
Control
AAUT1 AUT2 Pseudomonas fluorescens
Isolates Mean inhibition percentage by*
Bayleton Curzate Ridomil Sancozeb Mean ±SD
Pg.11 73.9±4.6a 69.5±13.4a 72.2±0.7c 85.5±2.0a 75.3±9.0a
Pg.20 70.7±7.0a 69.4±10.3a 80.5±3.0a 87.3±2.1a 77.0±9.5a
Pg.22 68.1±7.0a 67.0±12.1a 79.4±3.1ab 88.4±1.8a 75.7±11.1a
Pg.26 74.9±3.2a 73.3±11.3a 78.3±1.2ab 86.9±1.5a 78.3±7.6a
Pg.40 73.6±5.9a 75.3±9.9a 82.5±3.4a 88.0±3.3a 79.8±8.2a
Pg.41 70.1±5.4a 69.6±12.7a 75.7±4.3bc 86.6±1.4a 75.5±9.6a
Mean ±SD 71.9±5.6 70.7 ±10.7 78.1±4.3 87.1±2.1 76.9±9.2
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Table 10. Mean percent of mycelial growth inhibition of the test isolates on PDA amended with fungicides after 7days of incubation, at 27 ±1oC
Percich et al. (1997)
In vitro evaluation of fungicides cont’d….
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200PPM
500PPM
800PPM
1000PPM
Sancozeb
5. Conclusions and recommendations
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In Vitro evaluation of the effectiveness of biological agents on the
mycelia growth of the isolates, in general, showed that the
Pseudomonas fluorescence was less effective than the two
Trichoderma species (AUT1 and AUT2)
The most effective fungicide was found to be Sancozeb followed by
Ridomil, Bayleton, and Curzate.
The interspecific relative susceptibility of P. grisea isolates showed
a pattern of Pg.11 > Pg.22 > Pg.41> Pg.20> Pg.26> Pg.40 on all
fungicides.
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Recommendation
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ACKNOWLEDGEMENT
BioInnovate Eastern Africa
Bako Agricultural Research Center
Department of Microbial Cellular Molecular Biology,
Collage of Natural Sciences, Addis Ababa University.
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